Study On The Structure Deformation And Surrounding Surface Subsidence Of Deep Foundation Pit Of Rail Transit Metro Station In A Certain Area

The development of underground rail transit is the embodiment of improving the competitiveness of modern cities.With the increase of subway construction scale,the foundation pit of rail transit is developing in a deeper direction,the foundation pit excavated by underground rail transit project is mostly located in the center of densely populated city,which has the characteristics of deep,long and narrow,and the foundation pit engineering in different areas has strong regional difference.The lateral movement of the deep foundation side-wall and the subsidence of the road and ground around the foundation pit are the factors that directly reflect the safety of the foundation pit and surrounding environment,therefore,it is of great practical significance to analyze the supporting structure of the subway foundation pit and the deformation law of the surrounding surface to ensure the safety of engineering quality.The research of this paper is based on the foundation pit engineering of the rail transit line 3 in H city,in term of the geological conditions of station site and the surrounding environment,combining with the foundation pit supporting scheme,this paper formulated the project monitoring plan,and the construction of the subway station foundation pit engineering process real-time monitoring.According to the monitoring results,this paper summarizes the deformation law of the supporting structure and the road and ground around the foundation pit in the construction process,and analyzes the dynamic changes of surface settlement during the construction.In this paper,finite element software ANSYS is used to simulate the excavation process of subway foundation pit and end well,and analyzes the lateral movement of the support system and the displacement of the surrounding soil in the dynamic construction process and compared with the monitoring data,and verifies the feasibility of using 3d numerical modeling to study the displacement variation of deep foundation pit support system.Based on the strong regional characteristics of deep foundation pit engineering,this paper analyzes the measured data of 22 monitoring sections in 11 subway stations in the area of line 3 in H city,and studied the deformation characteristics and related factors of ground subsidence around the foundation pit in "inner support + support pile" supported by deep foundation pit in H city.This paper summarizes the distribution curve of surface subsidence around the foundation pit wall in H city,and makes the envelope diagram of settlement distribution,It provides reference for the prediction of surface subsidence and support design of similar deep foundation pit wall in subsequent H city.Finally,the prediction model of surface subsidence around foundation pit wall is constructed based on BP neural network,a certain amount of monitoring samples were used to train the neural network to predict the late settlement,In addition,the prediction error is discussed based on the measured data,which provides reference and advice for the deformation control of ground subsidence after the foundation pit wall of similar engineering.